The design rules of design circuits including semiconductors, etc., have been progressing further miniaturization of circuits year by year. Accompanied by this, with regard to the photomasks for forming circuits, the conditions required for the circuit pattern such as the line width, the shape and the pitch are increasingly strict.
As a forming method of a circuit, the photolithography method has heretofore been used, and as a resist composition for dealing with such miniaturization, a chemical amplification type resist suitable for a shorter wavelength and a higher resolution has widely been used.
The photolithography method using the chemical amplification type resist is a method for obtaining a desired circuit pattern in which a catalytic substance in the resist composition is formed by irradiation with light such as an excimer laser or irradiation of electron beam, and heat treatment is carried in the next step to react the catalytic substance and a polymer with each other, whereby the light or electron beam irradiated portion is solubilized (positive type) or insolubilized (negative type).
With regard to a photomask blank substrate container (hereinafter sometimes simply referred to as container) for storing or transporting a photomask blank substrate onto which a resist composition has been coated until the light or electron beam irradiation to the photomask blank substrate, light weight is desired since transportation or carrying is easy. In addition, a container using various polymer-based materials as a substrate, and produced by injection molding, etc., has conventionally been used in the points of being inexpensive and capable of being mass-produced.
However, various volatile components generating from the container comprising these polymer-based materials caused some influence on a catalytic action, a solubilizing action or insolubilizing action of the photoresist composition coated on the photomask blank substrate during storage or transportation of the photomask blank substrate. As a result, it sometimes caused inconvenience that, for example, a dimensional change such as enlargement or reduction of the line width was generated to the resist pattern on the photomask blank substrate formed by light or electron beam irradiation, heat treatment and development, and as a result, a pattern as designed could not be obtained.
To the problem caused by such a polymer-based material, it has been proposed a container comprising a thermoplastic resin in which an amount of caprolactam is 0.01 ppm or less in terms of n-decane per a weight of the resin by paying attention to the caprolactam in the outgas (for example, see Patent Literature 1).